The Methods Core (MC) will provide centralized services to address research questions and issues pertaining to study design, measurement, analysis, and methods training to the TCORS research projects, other cores, and investigators. The MC will assure that measurement and data collection approaches are refined to be useful in various vulnerable populations and will also pro-actively refine and adapt data collection tools for use in diverse vulnerable populations, providing an internal service and one that will be of value to the other TCORS. The MC will offer services and consultation on identification, development and validation of instruments, and provision of state-of-the-art, culturally appropriate interview, physiological, psychosocial, behavioral community-based, archival, GIS, and observational measures, data management, statistical analysis, training and methodological and statistical consultation. The MC will maintain a web- based system to provide a central repository for data and facilitate instrument and file sharing among Center investigators, regulatory science trainees, and other funded TCORS. The MC core members bring expertise in discipline-specific measurement, design, and analytic techniques, such as advanced methodologies, statistical modeling, psychometrics analysis, qualitative data analysis, community-based participatory research (CBPR) methods, and behavioral data collection. The Specific Aims of the Methods Core are: Design and Sampling. To assist in the review of research design protocols and to develop and implement appropriate sampling methodology for center studies and cores and to advise the Population Core on procedures for maximizing participation and tracking rates and minimizing attrition. Measurement Validation and Development. To assist in the identification of existing measures and development and validation of new measures that can be applied across projects. Data Management. To develop and maintain a website to serve as a centralized, secure web system to facilitate sharing of instruments and data sets across projects, conduct data entry for the projects. Data Analysis. To provide statistical and computer support for USC TCORS projects and regulatory science trainees, and to share new statistical methods with other TCORSs. Consultation, Training and Integration. To provide consulting to investigators and staff in measurement and analysis strategies, and collaborate in training in regulatory science methodologies with the Research Training and Education Core. RELEVANCE (See instructions): The Methods Core coordinates existing resources, procedures and expertise to make them available to all the investigators in the center, and provides guidance to all studies on study design, statistical analysis, and measurement development. The Methods Core will help to assure that the research of the USC TCORS is as informative as possible.